Flat-panel display devices, such as an organic electroluminescence (EL) display device and a liquid crystal display device, have been used in various fields. In recent years, as regards mobile information terminal devices such as mobile phones and PDAs (personal digital assistants), there has been an increasing demand for a display device having a less thickness and a less weight.
For example, such a technique has been proposed that all members constituting an electronic device are configured to be flexible by connecting a flexible display panel and a flexible driving circuit board via a flexible printed circuit. As another similar example, there has been proposed a technique in which a flexible printed circuit is connected to a flexible display panel. In addition, as another example, such a technique has been proposed that a flexible display panel module is sandwiched between two resin sheets, these two resin sheets are thermocompression-bonded, and a flexible printed circuit board, which is connected to an end portion of the display panel module, is also sandwiched between the two resin sheets, thereby enhancing sealing properties and ensuring protection against the external environment.
On the other hand, there has been a demand for simplifying a manufacturing process and improving productivity in achieving mass-production of display devices, while enhancing reliability.